The starting of a 3-phase induction motor connected to a single-phase supply system

Symmetrical component theory is used to express the relationship between the starting performance of a 3-phase induction motor, when connected to a single-phase supply system, and its normal starting performance in terms of two dimensioniess parameters. Performance characteristics applicable to machines of any rating are computed for a range of values of the two parameters, and various conditions for optimum operation are established. Accepted measures of starting quality are discussed critically, and a new criterion relating starting torque and stator copper loss is proposed. It is shown that best starting performance is given by a phase converter which simulates balanced 3-phase conditions in the machine, and experiments on a epical motor indicate that the corresponding run-up performance is likely to be satisfactory.